Inspect both trees for sturdiness and soundness. Each tree's diameter should be at least 7 inches to support 200 to 240 lbs. Look at each tree's trunk and foliage to ensure there are no diseases, canker or rot.
Stretch the hammock out between each tree to get an idea of how much rope you will need. For instance, if there is about 2 feet between each tree and the stretched-out hammock, you'll need about 28 feet of rope--14 feet for each end of the hammock.
Loop each rope through the end rings on either side of the hammock, then loop both ends around the base of the tree trunk. Leave the four ends untied at this point.
Put on eye protection and use the reciprocating saw to cut rubber garden borders to fit around the diameter of each tree, 6 or 7 feet from the ground. The rubber border will prevent the trees from damage as well as keep the rope from slipping.
Wrap the rubber garden border around the tree's trunk about 6 to 7 feet off the ground. Have a friend lift one side of the hammock along with the loose rope up to the rubber. Wrap the rope ends around the trunk four to five times, then tie a loose knot just to hold the rubber and rope in place. Repeat on the other end.
Measure the distance from the hammock's bottom in the middle to the ground. It should be about 4 to 5 feet off the ground. If it's too low, adjust the rubber borders and ropes accordingly to allow sufficient room for sagging when the hammock is being used. Tie off the ends with strong, tightly pulled knots.